IQ180+H2: how to turn off noise reduction for star trail images?

[rogerxnz]

I have an IQ180  and an H2 and want to try photographing star trails. The info I have relates to using DSLRs and all recommend making sure "NR (Noise Reduction) is set to OFF on your camera!!. Otherwise, the camera will spend equal amount of time (30 seconds) doing dark-frame subtraction resulting in gaps in your trails."

How do I stop the IQ180 from taking a dark frame? There is nothing about this in the IQ180's or the H2's manuals.
Roger

[Paul2660]

The only way I know of is put the camera in aerial mode. If that mode is available for the 180.

Paul C

[Doug Peterson]

I have an IQ180  and an H2 and want to try photographing star trails. The info I have relates to using DSLRs and all recommend making sure "NR (Noise Reduction) is set to OFF on your camera!!. Otherwise, the camera will spend equal amount of time (30 seconds) doing dark-frame subtraction resulting in gaps in your trails."

How do I stop the IQ180 from taking a dark frame? There is nothing about this in the IQ180's or the H2's manuals.
Roger

You can disable the dark frame by selecting Aerial Mode. But your results will be poor. The CCD sensor in the 180 cannot handle very well extended continuous shooting at the ISO and shutter speed combinations required for star trails. The IQ3 100mp or any of the Team Phase One 50mp backs would be a much better fit for this use case.

[rogerxnz]

Thank you both for your help.

Luckily, I am not excited by star trails and was only looking into them for a social meetup with a star trail theme!
Roger

[Christoph B.]

This might sound like a stupid question - but why turn of dark frame subtraction for star trails? Wouldn't the result benefit from a DFS by showing a clearer sky etc? The stars themselves won't be erased anyway - so if you turn off the noise reduction in CaptureOne that should be sufficient

[Paul2660]

If you stack, which is IMO the best way to shoot star trails, then you will have a gap, between each exposure.  So say your stack is 40 1.5 minutes, then you will get a corresponding gap for every exposure.  No easy way to fill this unless you use "star tracer", the only program I have found to fix such issues.  The dark frame must be the same amount of time as the previous exposure and on a Phase back this starts to effect anything at 1" or longer.

If you leave the exposure on for 1 long up to 1 hour exposure then you will have to take a corresponding 1 hour dark frame.  Now the IQ180 can't go there anyway, so it can only work with a stack type series of exposures. 

Here is a brief article I wrote a few years ago that explains more of this.

http://photosofarkansas.com/2014/09/23/092314-using-stacking-for-better-night-photography-results/

Paul C